Evaluation of Full Versus Fractional Doses of COVID-19 Vaccines Given as a Booster in Adults in Australia - Mongolia, Indonesia, Australia Coronavirus (MIACoV).

A Randomised Controlled Trial to Assess the Immunogenicity, Safety, and Reactogenicity of Standard-dose Versus Fractional Doses of COVID-19 Vaccines (Pfizer-BioNTech or Moderna) Given as an Additional Dose After Priming With Pfizer-BioNTech or AstraZeneca in Healthy Adults in Australia-MIACoV

This is a single-blind, randomised controlled clinical trial to determine the reactogenicity and immunogenicity of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) vaccines (Pfizer-BioNTech or Moderna) as booster dose in adults, who have previously received either Pfizer-BioNTech or AstraZeneca as their primary doses.

Both fractional and standard doses of Pfizer-BioNTech or Moderna will be tested.

The trial intervention will be given in line with Australian Technical Advisory Group on Immunisation (ATAGI) recommendations for booster vaccine doses which allows booster doses from 5 months onwards . There will be a total of 8 groups, with 100 individuals of even spread of participants above and below 50 years in each group. The trial will be single site, based at Royal Children's Hospital, Melbourne, Australia

As per brief summary

Inclusion Criteria:

1. Have completed two doses of Pfizer-BioNTech or AstraZeneca vaccines with the recommended schedule 6 months prior to the date of enrolment
2. Willing and able to give written informed consent
3. Aged 18 years or above
4. Willing to complete the follow-up requirements of the study

Exclusion Criteria:

1. Received 3 doses of COVID-19 vaccine
2. Received 2 doses of COVID-19 less than 6 months prior to the start of the trial
3. Received a different Covid-19 vaccine not available in Australia
4. Currently on immunosuppressive medication or anti-cancer chemotherapy
5. HIV infection
6. Congenital immune deficiency syndrome
7. Has received immunoglobulin or other blood products in the 3 months prior to vaccination
8. Study staff and their relatives
9. Have a history of a severe allergic reaction to any COVID-19 vaccines or have a medical exception to receiving further COVID-19 vaccines
10. Cannot read or understand English